<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框</title>
    <link rel="stylesheet" href="../../css/bootstrap.css">
    <link rel="stylesheet" href="../../bootstrap-icons-1.13.1/bootstrap-icons.min.css">
</head>
<body>
    <div class="container">
        <div class="border border-dark bg-danger">边框颜色</div>
        <!--宽度是bs5才有的-->
        <div class="border border-5">边框宽度</div>
        <br>
        <div class="border border-top-0">顶部无边框</div>
        <br>
        <div class="border border-right-0">右侧无边框</div>
        <br>
        <div class="border border-bottom-0">底部部无边框</div>
        <br>
        <div class="border border-left-0">左侧无边框</div>
        <hr>
        <div class="border rounded ">11111</div>
   </div>
</body>
</html>